IBM SG24-5360-00 manual What Is IXFP?, Deleted Data Space Release

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Figure 2. Data Snapping. SnapShot creates a logical copy by copying the FTD pointers.

Only when either the original or the copied track is updated is its associated FTD pointer changed to point to the new data location. The other FTD pointer remains unchanged. Additional space is needed in this case. As long as there is a pointer to a data block in the physical disk storage, the block cannot become free for the freespace collection process. A reference counter in the TNT prevents the block from becoming free.

Although the creation of the copy is a logical manipulation of pointers, the data exists on disk, so in this sense is not a logical copy. As far as the operating system is concerned, the two copies are completely independent of each other. On the RVA hardware side, the snap is a virtual copy of the data.

1.2.3 What Is IXFP?

The IXFP portion of IXFP/SnapShot for VSE/ESA provides two functions: DDSR and reporting.

1.2.3.1 Deleted Data Space Release

The RVA manages the freespace in the back-end storage by monitoring space that is no longer occupied by active data. This may be space formerly occupied by temporary files, such as DFSORT for VSE work files, or it may be space that previously held data that has been updated and written back to a different array track in the back-end storage of the RVA. The difference is that the RVA does not know that the sort work space is no longer needed without being explicitly told to release it into the free space pool.

The DDSR option of the IXFP operator command provides the ability to release this freespace back to the RVA. Using DDSR, allocated space can be returned to the RVA on a subsystem or volume basis. Individual files can also be deleted and their space returned. DDSR is done using the new IXFP Attention Routine command when space reclamation is needed. Either the operator can invoke the commands, or a job stream can include them.

4 RAMAC Virtual Array, Peer-to Peer Remote VSE/ESA

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Contents International Technical Support Organization Page International Technical Support Organization First Edition January Contents Peer-to-Peer Remote Copy Itso Redbook Evaluation Contents Vi Ramac Virtual Array, Peer-to Peer Remote VSE/ESA Preface Team That Wrote This RedbookComments Welcome Your comments are important to usOverview of RVA and the Virtual Disk Architecture What Is an IBM Ramac Virtual Array?IBM Ramac Virtual Array Log Structured FileData Compression and Compaction − Functional track tableVSE/ESA Support for the RVA What Is IXFP/SnapShot for VSE/ESA?What Is SnapShot? What Is IXFP? Deleted Data Space ReleaseWhat Is Peer-to-Peer Remote Copy? Reporting FunctionsRamac Virtual Array, Peer-to Peer Remote VSE/ESA Disk Capacity RVA Benefits for VSE/ESARVA Simplifies Your Storage Management Batch Window Improvement AdministrationIxfp Ramac Virtual Array IXFP/SnapShot for VSE/ESAHardware Application DevelopmentRVA Data Availability SnapShot PprcRamac Virtual Array, Peer-to Peer Remote VSE/ESA VSE/ESA Support for the RVA PrerequisitesHost Connection Volumes1 VSE/ESA Input/Output Configuration Program Assgn Volume Minimal InitPartial Disk Minimal Init ExecRamac Virtual Array, Peer-to Peer Remote VSE/ESA IXFP/SnapShot for VSE/ESA System VSE/ESA User TimeDTRIATTN,PARM=′ Ixfp REPORT′ Sample Batch Job to Invoke Ixfp Report FunctionIXFP/SnapShot for VSE/ESA AR 0015 CUU DEF DetailPhys DefinedFull Volume Ixfp SnapReply ′ YES′ to Proceed VSE/VSAMRange of Cylinders Non-VSAM File Expired Files Ixfp DDSR,PATEV30000-0999,NOPROMPT Total VolumeIxfp DDSR,PATEV3 Specified File Ixfp DDSR,PATEV3DSN=′ test.data.3′ , NopromptIxfp Report Ixfp REPORT,80E Ixfp REPORT,80FIxfp REPORT,80E,80F Sample Output of Ixfp Report Command Device Detail ReportRamac Virtual Array, Peer-to Peer Remote VSE/ESA Device Summary Report Subsystem Summary ReportRamac Virtual Array, Peer-to Peer Remote VSE/ESA Peer-to-Peer Remote Copy Peer-to-Peer Remote CopyPprc and VSE/ESA Software Requirements Pprc Data FlowPprc Hardware Requirements Invoking peer-to-peer remote copyPrimary Devices of a Pprc Pair Examples of Pprcopy CommandsSnapShot Considerations Secondary Devices of a Pprc PairSetting Up Pprc Paths and Pairs Recovering from a Primary Site FailurePhysical Connections to the RVA Recovering from a Secondary Site FailureDeleting Pprc Pairs and Paths Determining the Logical Control Unit Number for RVA Determining the Channel Connection AddressRamac Virtual Array, Peer-to Peer Remote VSE/ESA Appendix A. RVA Functional Device Configuration Functional Device ConfigurationFunctional Device Configuration Screen CD23 Syntax Appendix B. Ixfp Command ExamplesSnap Command Ramac Virtual Array, Peer-to Peer Remote VSE/ESA Using SnapShot to Copy One Volume to Another NopromptTest Prod Overall Test Prod AR 0015 CapacityDEFINED-CAPACITY Using SnapShot to Copy a File from One Volume to Another Using SnapShot to Copy Files with RelocationOther Uses of SnapShot IXFP20I Snap Function Completed ATDdsr Command Syntax of Ixfp Ddsr Command DetailsUsing Ddsr to Delete a Single Data Set Using Ddsr to Delete the Contents of a VolumeAR+0015 IXFP29D Ddsr for For Deletion Using Ddsr to Delete the Free Space on an RVAReport Report Command Reporting on the Capacity of the RVA Subsystem Reporting on the Capacity of a Single VolumeReporting on the Capacity of Multiple Volumes Device Detail Report FUNC. Capacity MBExec DTRIATTN,PARM=′ Ixfp REPORT′ IXFP/SnapShot Setup Job StreamsJOB WCWTEST1 Ixfp DDSR,80E BG 0000 // JOB InitdiskBG 0000 1A86I Following Assignments are Released Ready Ixfp DDSR,80F50.83 47.86 AR 0015 1I40I Ready $$DITTO BLKFACTOR=1 EOJ$$DITTO BLKFACTOR=1 $$DITTO EOJ 726532.208 MB 117880.209 MB 57754.953 MB Appendix C. VSE/VSAM Considerations Backing up Vsam Volumes Appendix C. VSE/VSAM Considerations Ramac Virtual Array, Peer-to Peer Remote VSE/ESA Appendix D. Iocds Example Ramac Virtual Array, Peer-to Peer Remote VSE/ESA Appendix E. Special Notices Following terms are trademarks of other companies Redbooks on CD-ROMs Appendix F. Related PublicationsInternational Technical Support Organization Publications Other PublicationsRamac Virtual Array, Peer-to Peer Remote VSE/ESA How to Get Itso Redbooks ∙ E-mail OrdersIBM Redbook Fax Order Form Please send me the followingIndex See CKDPprc distance Itso Redbook Evaluation Please answer the following questionsSG24-5360-00